Year	Number
2004-01-01	18
2005-01-01	20
2006-01-01	20
2007-01-01	20
2008-01-01	22
2009-01-01	21
2010-01-01	21
2011-01-01	16
2012-01-01	13
2013-01-01	10
2014-01-01	8